Back to EveryPatent.com
United States Patent | 5,734,586 |
Chiang ,   et al. | March 31, 1998 |
The present invention features a direct, closed-loop method for controlling an unbalanced, power-distribution network having a great number of nodes, branches and laterals, as well as multiphase loads. The network has a radial structure. One or more formulae are first derived for a power-distribution network. The formulae may be an explicit loss formula, a voltage formula, a line flow formula or any combination thereof. Network flow programming techniques which incorporate the formulae are then developed to directly achieve steady state. Finally, the control steps are performed on the power-distribution network in real time to control its operation. The control steps may include placing a capacitor, regulator or switch at a specific position in the network and/or reconfiguring the network in some other manner.
Inventors: | Chiang; Hsiao-Dong (Ithaca, NY); Wang; Jin-Cheng (Sunnyvale, CA) |
Assignee: | Cornell Research Foundation, Inc. (Ithaca, NY) |
Appl. No.: | 436036 |
Filed: | May 5, 1995 |
Current U.S. Class: | 700/286; 307/31; 307/35; 307/38; 307/39 |
Intern'l Class: | H02J 003/14; H02J 003/16; H02J 003/12; G05B 013/04 |
Field of Search: | 307/31,35,38,39 323/209 340/825.06 364/148,492,493,494 |
2976480 | Mar., 1961 | Johnson | 323/209. |
3002146 | Sep., 1961 | Lorrig et al. | 323/209. |
3002147 | Sep., 1961 | Wasserman | 323/209. |
3063003 | Nov., 1962 | Pirhofer | 323/209. |
4264960 | Apr., 1981 | Gurr | 364/492. |
4769587 | Sep., 1988 | Pettigrew | 323/209. |
5420495 | May., 1995 | Hingorani | 323/318. |
5422561 | Jun., 1995 | Williams et al. | 323/209. |
5517423 | May., 1996 | Pamatto | 364/492. |
5608646 | Mar., 1997 | Pomatto | 364/492. |
5610834 | Mar., 1997 | Schlueter | 364/492. |
Baldick, R., & F. F. Wu 1990. "Efficient Integer Optimization Algorithms for Optimal Coordination of Capacitors and Regulators". IEEE Trans. On Power Systems, vol. 5., No. 3, Aug.:805-812. Baran, M. E., & F. F. Wu. 1993. "Network Reconfiguration in Distribution Systems for Loss Reduction and Load Balancing". IEEE Trans. On Power Delivery. vol. 4, No. 2, Apr.:1401-1407. Baran, M. E. And F. F. Wu. 1989. "Optimal Capacitor Placement on Radial Distribution Systems". IEEE Trans. On Power Delivery. vol. 4, No. 1, Jan.:725-734. Bishop, M. T. & Lee, R. E. 1986. "Distribution System Line Loss Reduction Through Enhanced Capacitor Location Techniques". IEEE Trans. on Power Delivery. vol. 1, No. 2, Apr.:190-197. Broadwater, R. P., Kahn, A. H., Shaalan, H. E., & Lee, R. E. 1993. "Time Varying Load Analysis To Reduce Distribution Losses Through Reconfiguration". IEEE Trans. On Power Delivery. vol. 8, No. 1, Jan.:249-300. Chen, T. H., M. S. Chen, K. J. Hwang, P. Kotas & E. A. Chebli. 1991 "Distribution System Power Flow Analysis--A Rigid Approach". IEEE Trans. on Power Delivery. vol. 6, No. 3, Jul.:1146-1152. C. S. Chen & Cho, M. Y. 1993 "Energy Loss Reduction by Critical Switches". IEEE Trans. On Power Delivery. vol. 8, No. 3, Jul.:1246-1253. Hsiao-Dong Chiang, Jin-Chen Wang, O. Cockings & H. D. Shin. 1990. "Optimal Capacitor Placements in Distribution Systems: Part I: A New Formulation and Overall Problem". IEEE Trans. on Power Delivery. vol. 5, No. 2, Apr.:634-642. S. Civanlar, J. J. Granger. 1985. "Volt/Var Control on Distribution Systems with Lateral Branches Using Shunt Capacitors and Voltage Regulators: Part I, Part II, Part III". IEEE Trans. On Power Apparatus and Systems. vol. 104, Nov.:3278-3297. A. A. El-Kib, J. J. Grainger, K. N. Clinard, L. J. Gale. 1985. "Placement of Fixed and/or Non-Simultaneously Switched Capacitors on Unbalanced Three-Phase Feeders Involving Laterals". IEEE Trans. On Power Apparatus and Systems. vol. 104, Nov.:3298-3305. S. K. Goswami, & S. K. Basu. 1992 "A New Alogoritm for the Reconfiguration of Distribution Feeders For Loss Minimization". IEEE Trans. On Power Delivery. vol. 7, No. 3, Jul.:1484-1491. J. J. Grainger, & S. H. Lee. 1982. "Capacitor Release by Shunt Capacitor Placement on Distribution Feeders: A New Voltage-Dependent Model". IEEE Trans. On Power Apparatus and Systems. vol. 101, May:1236-1244. J. J. Grainger, S. H. Lee, A. A. El-Kib. 1982. "Design of A Real-time Switching Control Scheme for Capacitive Compensation of Distribution Feeders". IEEE Trans. On Power Apparatus and Systems. vol. 101, Aug.:2420-2428. K. H. Jung, H. Kim, Y. Ko. 1993 "Network Reconfiguration Algorithm for Automated Distribution Systems Based on Artificial Intelligence Approach". IEEE Trans. On Power Delivery. vol. 8, No. 4, Oct.:1933-1941. H, C. Kuo & Y. Y. Hsu. 1993 "Distribution System Load Estimation and Service Restoration Using a Fuzzy Set Approach". IEEE Trans. On Power Delivery. vol. 8, No. 4, Oct.:1950-1957. R. E. Lee & C. L. Brooks. 1988 "A Method and its Application to Evaluate Automated Distribution Control". IEEE Trans. On Power Delivery. vol. 3, No. 3, Jul.:1232-1240. S. H. Lee & J. J. Grainger. 1981 "Optimum Placement of Fixed and Switched Capacitors on Primary Distribution Feeders". IEEE Trans. On Power Apparatus and Systems. vol. 100, Mar.:45-352. G. X. Luo & A. Semlyen. 1990. "Efficient Load Flow for Large Weakly Meshed Networks". IEEE Trans. On Power Systems. vol. 5, No. 4, Nov.:1309-1316. J. Qiu & S. M. Shahidehpour. 1987. "A New Approach For Minimizing Power Losses and Improving Voltage Profile". IEEE Trans. on Power Systems. vol. PWRS-2, No. 2, May:287-295. D. W. Ross, J. Patton, A. I. Cohen and M. Carson. 1981. "New Methods for Evaluating Distribution Automation and Control (DAC) Systems Benefits". IEEE Trans. On Power Apparatus and Systems. vol. 100, No. 6, Jun.:2978-2986. M. M. A. Salama, E. A. A. Mansour, A. Y. Chikhani and R. Hackam. 1985. "Control of Reactive Power in Distribution Systems with an End-Load and Varying Load Condition". IEEE Trans. on Power Apparatus and Systems. vol. 104, pp. 941-947. D. Shirmohammadi, H. W. Hong, A. Semlyen and G. X. Luo. 1988. "A Compensation-based Power Flow Method for Weakly Meshed Distribution and Transmission Networks". IEEE Trans. On Power Systems. vol. 3, No. 2, May:753-762. D. Shirmohammadi, H. W. Hong. 1989. "Reconfiguration of Electric Distribution Networks for Resistive Line Losses Reduction". IEEE Trans. on Power Deliver. vol. 41, No. 2, Apr.:1492-1498. T. Taylor & D. Lubkeman. 1990. "Implementation of Heuristic Search Strategies for Distribution Feeder Reconfiguration". IEEE Trans. On Power Delivery. vol. 5, No. 1, Jan.:239-246. Jin-Cheng Wang, Hsiao-Dong Chiang, Gary Darling. "Optimal Capacitor Placement and Real Time Control in Large-Scale Unbalanced Distribution Systems: Numerical Studies". Submitted to 95 IEEE Winter Power Meeting, New York. Chen et al;, "Determination of Critical Switches in Distribution System"; IEEE Transactions on Power Delivery; vol. 7 No. 3, Jul. 1992; pp. 1443-1449. |
TABLE I ______________________________________ A comparison of the total, real power loss from both a loss formula and a standard, three-phase, power flow method Three Phase Systems power flow Loss Formula Error % ______________________________________ 101 102.491 101.569 -0.900 151 234.073 235.842 0.756 191 256.703 258.862 0.841 231 339.362 343.520 1.225 291 400.499 406.655 1.537 394 579.708 554.722 -4.310 ______________________________________
TABLE II ______________________________________ A comparison of the total real power loss from both a loss formula and a standard, three-phase power flow method Three Phase Load Factor Power Flow Loss Formula Error % ______________________________________ 0.5 133.668 133.206 -0.346 0.7 245.124 246.703 0.644 0.9 390.624 396.546 1.516 1.1 565.692 579.793 2.493 1.3 766.205 794.101 3.641 1.5 988.395 1037.725 4.991 ______________________________________
TABLE III ______________________________________ A comparison of the total real power loss from both a loss formula and a standard, three-phase, power flow method Three Phase Capacitor Sizes Power Flow Loss Formula Error % ______________________________________ 0 497.042 506.040 1.810 300 466.761 473.829 1.514 600 460.227 471.991 2.556 900 480.708 500.526 4.123 1200 531.911 559.435 5.175 1500 618.043 648.716 4.963 ______________________________________